Rott R, Reinacher M, Orlich M, Klenk H D
Arch Virol. 1980;65(2):123-33. doi: 10.1007/BF01317323.
The spread of infection in the chorioallantoic membrane (CAM) has been analysed with pathogenic and non-pathogenic avian influenza A viruses. After allantoic inoculation of pathogenic strains, high titers of infectious virus were found in the allantoic fluid, and virus growth could be demonstrated by immunohistology and electron microscopy in the allantoic epithelium, the mesenchyma, and in the chorionic epithelium. By the same route of inoculation, non-pathogenic strains yielded also higher titers of infectious virus in the allantoic fluid, but virus replication was restricted to the allantoic epithelium and did not occur in the other cell layers. After chorionic inoculation of pathogenic strains, replication occurred in all layers of the CAM, and infectious virus was released into the allantoic fluid. However, when the chorionic epithelium was infected with a non-pathogenic strain, infection did not spread beyond the site of inoculation. These differences in virus spread are based on differential activation of the hemagglutinin by proteolytic cleavage. The hemagglutinin of pathogenic strains is cleaved in cells of each layer, whereas the hemagglutinin of non-pathogenic strains is cleaved only in the allantoic epithelium. In epithelial cells, virus budding occurred nearly exclusively at the apical side of the cell surface, but this polarization of virus maturation was found with both pathogenic and nonpathogenic strains, indicating that it does not account for the differences in virus spread and, thus, in pathogenicity.
已使用致病性和非致病性甲型禽流感病毒分析了绒毛尿囊膜（CAM）中的感染传播情况。在对致病性毒株进行尿囊接种后，在尿囊液中发现了高滴度的感染性病毒，并且通过免疫组织学和电子显微镜可在尿囊上皮、间充质和绒毛膜上皮中证实病毒生长。通过相同的接种途径，非致病性毒株在尿囊液中也产生了更高滴度的感染性病毒，但病毒复制仅限于尿囊上皮，在其他细胞层中未发生。在对致病性毒株进行绒毛膜接种后，CAM的所有层均发生复制，并且感染性病毒释放到尿囊液中。然而，当绒毛膜上皮感染非致病性毒株时，感染并未扩散到接种部位以外。病毒传播的这些差异基于蛋白水解切割对血凝素的不同激活作用。致病性毒株的血凝素在各层细胞中被切割，而非致病性毒株的血凝素仅在尿囊上皮中被切割。在上皮细胞中，病毒出芽几乎仅发生在细胞表面的顶端，但致病性和非致病性毒株均存在病毒成熟的这种极化现象，这表明它不能解释病毒传播以及致病性方面的差异。
